<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript">
        var a = "12";
        var b = 12;
        //做字面值的比较
        alert(a == b);//true

        //做字面值的比较和数据类型的比较
        alert(a === b)//false
    </script>
</head>
<body>

</body>
</html>